Poly(ester-amine salt)(PEAS) precursor powders were synthesized via esterification process with aromatic dianhydride and diamine as monomers in the mixed solvent consisting of methanol and tetrahydrofuran. Polyimide foams with uniform cells were prepared from PEAS with powder process. The structure and heat-resistant property of the polyimide foams were characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR) and thermogravimetry(TG). The influences of initial heating temperature and particle size of the powders on foam density were studied. The results show that the higher the initial heating temperature, the lower the foam density, the lesser the influence of the particle size of the powders on the foam density.